TextBox.OnTextChanged Method
Assembly: System.Web (in system.web.dll)
The TextChanged event is raised when the content of the text box changes between posts to the server.
Note: |
|---|
| A TextBox control must persist some values between posts to the server for this event to work correctly. Be sure that view state is enabled for this control. |
Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.
The OnTextChanged method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
Notes to Inheritors: When overriding OnTextChanged in a derived class, be sure to call the base class's OnTextChanged method so that registered delegates receive the event.The following code example demonstrates how to override the OnTextChanged method so that it always marks a custom TextBox server control as having been modified.
Security Note: |
|---|
| This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview (Visual Studio). |
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Custom TextBox - OnTextChanged - VJ# Example</title>
</head>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom TextBox - OnTextChanged - VJ# Example</h3>
<aspSample:CustomTextBoxOnTextChanged
id="TextBox1"
autopostback=true
runat="server"
text="Hello World!">
</aspSample:CustomTextBoxOnTextChanged>
</form>
</body>
</html>
package Samples.AspNet.JSL.Controls;
public class CustomTextBoxOnTextChanged
extends System.Web.UI.WebControls.TextBox
{
private boolean isDirty = false;
protected void OnTextChanged(System.EventArgs e)
{
// Call the base OnTextChanged method.
super.OnTextChanged(e);
// Change the dirty flag to True.
isDirty = true;
} //OnTextChanged
} //CustomTextBoxOnTextChanged
Note: